The San Diego Humane Society and SPCA announced Tuesday that its president, Mark Goldstein, won’t return from an extended leave of absence. A replacement is expected by early 2012 for one of the region’s oldest nonprofits.

No reason was given for Goldstein’s departure, and Goldstein declined to provide one in a brief telephone interview in which he said he’d talk more when negotiations with the agency over the separation end in a week or so.

Eleven months ago, San Diego Humane Society board Chairman Fred Baranowski strongly endorsed Goldstein in a period of tumult and criticism, but Baranowski was tight-lipped Tuesday, citing “strict state and federal laws.”

The leave was not previously publicized. A legislator sent out a statement in Goldstein’s name after a state Assembly vote four months ago, but Baehr said the quote had been recycled from a release in March.

The 130-year-old organization was embroiled in controversy in October when 17 former board members signed a letter questioning its animal-welfare policies and criticizing, in particular, its euthanasia record.

The San Diego Humane Society and others touted a goal to end euthanasia of adoptable or treatable pets in the county by 2005 while soliciting money for a capital campaign. Instead, the number of treatable animals put down by the county tripled from 2004 to 2010, the U-T Watchdog and 10News reported in the fall.

Baranowski, chairman of the organization’s board for the past three years, said Goldstein’s departure was not related to performance, last year’s controversy or any disciplinary matter.

Baranowski said the board selected an interim president a week and a half ago because of “Dr. Mark’s inability to return.” He said Goldstein initially requested a 90-day leave in early April, then received two 30-day extensions.

“The truth is it’s straightforward,” Goldstein said. “I’m glad to see people have put to rest any kind of evil undoing or something, but right now my comment would be we’re finishing up our discussions on our separation, and I’d like to finish those first before I make any further comment.”

Goldstein, 58, has been the organization’s president since 2001. He previously served as vice president of the San Francisco SPCA and in the 1990s was director of the Los Angeles Zoo. He also worked at the Massachusetts SPCA’s Angell Memorial Animal Hospital in Boston.

The San Diego society’s chairman said Goldstein’s salary was “confidential,” but its most recent tax documents show he earned $249,190 in total compensation, including $215,455 in base pay.

Jeff Lyle, who served on the agency’s board from 2002 to 2008 and was one of the most vocal critics of the organization last year, said Tuesday he had heard rumors about Goldstein being on a leave of absence for several months.